This invention relates generally to method and apparatus for the processing, manufacture and handling of thin wafers, and more particularly, the preparation of very thin semiconductor wafers to enable manufacture of very thin semiconductor devices.
Modern electronic equipment and particularly consumer portable electronic equipment relies heavily on using semiconductor devices. Much of this equipment is small and the trend is to make it smaller still. To achieve smallness in consumer products and an ability to perform various functions, these units or systems (consumer products) require thin semiconductor devices for operations. For example modern cell phones which in the last decade have become essential for substantially the entire public, are being put to many new and challenging applications and to perform these applications, these phones require a number of semiconductor devices to be housed within small compartments. In particular, cell phones are today being asked to browse the web, to upload videos, to download music and ring tones, provide information based on satellite navigation systems, to act as hand calculators and/or reminder calendar and/or memory of various other information, to send and receive messages and to take and send photos among other things. Thus these units require semiconductor devices beyond those useful only for telephone purposes. At the same time the public requires that the phones themselves be made smaller and lighter. The demands on such consumer units can only be achieved with the limited space available for these various functional devices if one fits more semiconductor devices into the small space available or into a smaller space than that available today as to create an even smaller and lighter consumer product. Otherwise the handset for example of a telephone must get bigger and bigger and heavier and heavier. This is not acceptable to the general public. These same comments fit modern laptop computers as well as other consumer products such as music recorders. We no longer want laptops for example that weigh 6 to 8 pounds. Instead we ask that the new units weigh half of that amount and have more capabilities than their predecessor units. This can only be achieved with lighter and more efficient semiconductor devices.
A solution to this challenge is to add more circuitry on the semiconductor. This of course is being attempted at all times. Another, which obviously is to be combined with the increases of circuits is to work with thinner wafers that in turn are used to make thinner semiconductor devices. For example, a typical wafer today has a thickness of about 750 microns and devices made from such wafers have a similar thickness. If one can reduce the thickness of the semiconductor device to about 50 microns, this would enable one to fit a number of such devices, for example, one on top of another, in the space that previously had been occupied by a single such device. A further benefit to having thinner devices is that during operation as part of a consumer product, semiconductor devices heat. The thicker the device the slower the dissipation of the heat. Thus the creation of thinner semiconductor devices has the further benefit of creating units that because of their ability to cool more rapidly operate more effectively for their intended purpose. Obviously, if the thickness is reduced, there is also a desired reduction in weight of the consumer products that use these semiconductor devices.
A problem that arises however is how to manufacture extremely thin semiconductor devices without destroying the wafers out of which they are made. Modern wafer making equipment can deal with wafers that are 750 microns thick. The equipment was designed for such wafers. Various manufacturers also include wafer-handling systems in processing units they manufacture and such units also can handle wafers that are 750 microns thick. However, when a wafer is reduced to approximately 50 microns in thickness, approximately 1/15th the thickness of wafers being handled in present day wafer handling equipment, the wafers become extremely brittle. If in addition the diameters of wafers used in manufacturing are either at the largest size since this brings about efficiencies in manufacturing or as typically is the case, about 300 mm in diameter, handling such wafers with existing equipment generally results in damage to wafers which will readily snap or break as moved from support system to support system and are then either useless or too expensive for making operable semiconductor devices.